Coal mining



FIP'Yti Patented Dec. 8, 1936 eioeanai titration l Carl Scholz,Charleston, W. Va.

No Drawing. Application Jilly 3.1 935,

Serial No. 29,736

6 Claims. (01. 262-1) My invention relates to a method for preventingthe formation of dust in the mining of coal, as well as in thesubsequent handling of it by the dealer and user.

Dust in coal mines originates from two sources: first, by the operationsof mining, such as shearing and cutting by machines, blasting andhandling from the face of the seam to the surface; and second, by theliberation of the fine dust which lies between the faces and beddings ofthe coal in the seam.

In the latter case, this dust probably originated when the coal measureswere subjected to a process of. bending and warping due to the movementof geological measures. This dust is impalpably fine, running betweenone hundred and two hundred mesh, and while the quantity is very small,the fact that it fills the crevices,

. which in gassy mines contain highly inflamma- Q blegases, makes it farmore dangerous than the dust generated by the process of mining, and itmay become ignited by blast shots" or other causes when brought incontact with sufficient oxygen.

Dust produced by the process of mining, upon exposure to'the atmospheregradually diminishes in hydrocarbon and therefore becomes lesscombustible, whereas the fine dust in the faces retains the full amountof gas and is far more dangerous. Coal dust of sufficient fineness willexplode with a mixture of one-eighth of an ounce of dust for each cubicfoot of air.

Moreover, when an explosion is well started, the floor dust, evenincluding some of the coarse material such as ZO-mesh size or larger,enters actively into aiding the extension of the flame and violence.Hence coal dustiness is dangerous whether on the floor or on the ribs,roof or timbers and an explosion may be initiated from finely divideddust in any of these places.

Very finely divided coal, however, that is thoroughly wet with suitable.liquids is practically free of the danger of either ignition orpropagation in connection with explosions.

One of the objects of my invention, therefore, is to provide a methodfor treating the coal with a suitable liquid to prevent ignition of thecoal dust in the vein.

A further object is to fill the crevices in the coal seams with aliquid, thereby displacing gas lying in the seam, reducing the amount ofexplosives required, preventing shattering of the coal and therebygreatly increasing the percentage of coarse coal.

A still further object of the invention consists in the introduction ofan aqueous solution of a deliquescent salt or crude oil which willprevent dust, not only in the mine but also in the handling and using ofthe coal after it has left the mine.

With these and other objects in view my invention consists in certainnovel features as will be hereinafter'more fully described and partic;

ularly pointed out in the claims.

In carrying out my process, I drill a number of holes in the coal seamand then before shooting the coal; force in a suitable liquid-such aswater, crude oil or an aqueous solution of adeliquescent salt, undervery high pressure, ranging from about 400 to 800 pounds per squareinch, depending upon the physical structure of the coal seam. Theseholes should preferably be drilled and treated before the coal isundercut, otherwise, since a very applied, the liquid not saturate thecoal in the back of the hole to thefaca' h The present practice is toundercut the coal first and drill the blasting holes afterwards but Ihave discovered that it is preferable to drill the holesfirst, injectthe liquid and then undercut, in order to pr vent the mining machinecuttings from gettinginto the'ventilating cur rents. The holes in whichthe liquid is injected can be used for shooting the coal down and noother or special holes need be drilled. Subject to the abovedisadvantages, the holes may be drilled after undercutting and still bewithin the spirit of the invention and additional holes may be drilledover the blasting holes in order to obtain complete saturation.

The necessary number of holes having been drilled, the liquid is forcedinto the holes under the desired pressure. Any suitable form ofapparatus may be used for forcing the liquid in the holes as will bereadily apparent to those skilled in the art.

For a suitable liquid, I may use water, or crude oil or a strong aqueoussolution of calcium chloride or other deliquescent salt. The advantageof using this kind of a salt solution resides in the fact that after thewater of solution has evaporated, crystals of calcium chloride will bedeposited on the coal. Subsequently these crystals deliquesce or breakdown giving up the Water of crystallization and in this way a moistcoating is made on the coal. Any of the fine dust that is wetted withthe salt solution will be kept wet longer than with water and thusprevented from exploding. The dust highpressure is will percolatethrough d,

on the coal that is being distributed to the consumer will also beprevented from drying out.

By forcing the liquid directly into the coal seam, the desired resultscan be attained with a less quantity than if the coal is sprayed withthe liquid.

By following my invention, the entire output of the mine can be madedustless before it is brought to the surface and at a minimum cost. Itis superior to a process of spraying certain sizes on the tipple or inthe dealers yard, where the liquid covers only the surface of the coalbecause in my process, the dust allaying liquid penetrates all of thecoal.

Some of the advantages of my process are:

First-Safety.-The introduction of a liquid, under pressure, into thecoal vein drives out the gases existing between the faces and in thecrevices of the coal-bed and moistens the very fine, but highlyinflammable dust, which is liberated by blasting. It allays the dustcreated by the undercutting machines, which is a great menace to safetyand is injurious to machine operators. Where grain or pellet powder isused, the moisture prevents the ignition of coal which frequentlyresults in serious mine fires. The elimination of cutter bar dust is oneof the greatest safety features sought by the coal mining industry.

Second-Economy.-The filling of crevices in the coal seam with liquidrenders it more resistant to the explosive, thus requiring lesserquantities, which in turn results in larger percentage of the coarsersizes.

Third-Sales advantages.The use of the liquid in drill holes willthoroughly saturate the vein and a smaller quantity will producesuperior results than can be obtained by spraying.

By drilling and treating the working faces with power drills used inconnection with the processing equipment, the labor costs will be nogreater than where holes are drilled by hand and better results will beobtained from this method, than if left to the individual coal loader. Acorresponding reduction in loading rates would be made if drilling andshooting is performed by the mining company. The

processing is performed by one or more small outfits depending upon thetonnage to be treated and the quantity of fluid used can be accuratelymeasured, depending upon the requirements of the trade.

The liquid that is employed may contain pigments, or other coloringmaterial or powdered metallic bronze, such as is used in paints, whichwill impart a certain sheen to the coal, giving it a distinctive color,which can be used as a. trademark to identify the origin of the coal.The color or metallic luster will not show up in all coals, but in thesplint variety, where the faces are filled with fine dust, the colorwill show up clearly.

I claim:

1. In the mining of coal, the steps comprising drilling holes in thecoal seam and then forcing a liquid under high pressure into the seamfor the purpose of preparing the coal for shooting, undercutting thecoal and then shooting the coal.

2. In the mining of coal, the steps comprising drilling holes in thecoal seam and then forcing oil under pressure into the seam for thepurpose of preparing the coal for shooting, undercutting the coal andthen shooting the coal.

3. In the mining of coal, the steps comprising drilling holes in thecoal seam and then forcing a liquid under a pressure of 400 to 800pounds per square inch into the seam for the purpose of preparing thecoal for shooting, undercutting the coal and then shooting the coal.

4. In the mining of coal, the steps comprising drilling holes in thecoal seam, forcing oil under high pressure into the holes to allay thedust, undercutting the coal and then shooting the coal.

5. In the mining of coal, the steps comprising drilling holes in thecoal seam, forcing oil under high pressure into the holes to allay thedust and using the said holes as blasting holes for shooting the coal.

6. In the mining of coal, the steps which comprise drilling holes in thecoal seam, forcing oil under high pressure into the holes to allay thedust prior to shooting the coal.

CARL SCHOLZ.

